P (x) = x^3+4x^2-8x-6

a = - 2

Unfortunately, you haven't shared the instructions for this problem. My guess is that you are to evaluate P (x) = x^3+4x^2-8x-6 for x = a = - 2.

If that's the case, then

P (-2) = (-2) ^3 + 4 (-2) ^2 - 8 (-2) - 6. This simplifies to:

= - 8 + 16 + 16 - 6 = 18 (answer)